JP6651759B2 - Non-oriented electrical steel sheet and manufacturing method thereof - Google Patents

Description

  The present invention relates to a non-oriented electrical steel sheet and a method for manufacturing the same. More specifically, the present invention is a non-oriented electrical steel sheet that is preferably used mainly for a core of a high-efficiency motor, such as a compressor motor for an air conditioner or a refrigerator, a drive motor and a generator for an electric vehicle or a hybrid vehicle, and the like. It relates to the manufacturing method.

  Due to the need to reduce greenhouse gases, products with low energy consumption have been developed in the fields of automobiles, home appliances, and the like. For example, in the automotive field, there are low fuel consumption vehicles such as a hybrid vehicle having a drive system combining a gasoline engine and a motor and an electric vehicle driven by a motor. In the field of home appliances, there are high-efficiency air conditioners, refrigerators, and the like that consume less electricity per year. The technology common to these is a motor, and increasing the efficiency of the motor is an important technology. In order to reduce the size, output and efficiency of motors, non-oriented electrical steel sheets, which are core materials, are required to have improved magnetic flux density and reduced iron loss under high frequency conditions.

  The magnetic properties of a non-oriented electrical steel sheet generally use the average of the rolling direction (L direction) and the direction perpendicular to the rolling direction (C direction) as an evaluation index. However, in the case of a one-punch motor, the magnetic flux flows in all directions in the plane of the non-oriented electrical steel sheet, which is a core material, so that the magnetic characteristics in the direction (D direction) that forms 45 ° with respect to the rolling direction are also reduced. Cases used as evaluation indicators are increasing.

  As means for improving the magnetic properties in the D direction, for example, Japanese Patent Application Laid-Open No. H11-163,1992 discloses a method for producing a non-oriented electrical steel sheet by performing cold rolling twice including intermediate annealing and then performing finish annealing. The crystal grain size before the second cold rolling was controlled in the range of 10 to 60 μm, the recrystallization rate after the intermediate annealing was controlled in the range of 30 to 85%, and the second cold rolling reduction was 3%. A method of reducing the content by 30% is disclosed. Further, Patent Document 2 discloses a method of performing a finish annealing after a product thickness is reduced by one cold rolling. In a case where a hot-rolled sheet annealing is performed, a cold rolling rate and a finish annealing condition of the cold rolling are set. Means for defining the conditions of the finish annealing when the hot rolled sheet annealing is not performed are disclosed. Patent Document 3 discloses a method for producing a non-oriented electrical steel sheet in which hot-rolled sheet annealing is performed, cold-rolled, and finish-annealed, and the average crystal grain size after hot-rolled sheet annealing is set to 300 μm or more. A means for controlling the path schedule is disclosed. However, these are mainly means for improving magnetic flux density, and reduction of high-frequency iron loss has not been studied.

JP 2001-49402 A JP 2005-307258 A JP 2006-291346 A

  SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object L-direction and C-direction suitable for use in drive motors and generators of electric vehicles and hybrid vehicles, and compressor motor cores of air conditioners and refrigerators. And a non-oriented electrical steel sheet having good magnetic properties in the D direction and a method for producing the same.

  The present inventors have conducted intensive studies to solve the above-mentioned problems, and in order to improve the magnetic properties in the L direction, the C direction and the D direction, annealing is performed under predetermined conditions before final cold rolling. It has been newly found that it is effective to perform the finish annealing after the annealing is performed under the condition that the cold pressure ratio of the rolling is set to a predetermined condition and the recrystallization is not generated. The gist of the present invention based on such new knowledge is as follows.

That is, in the present invention, C: 0.01% or less, Si: 1.0% or more and 4.0% or less, Al: 0.001% or more and 3.0% or less, and Mn: 0.05% by mass%. Not less than 3.0%, P: 0.15% or less, S: 0.01% or less, N: 0.01% or less, the balance being Fe and impurities, and satisfying the following formula (1). It has a microstructure having an average crystal grain size of 40 μm or more and 250 μm or less, a plate thickness of 0.10 mm or more and 0.35 mm or less, and an integrated strength of ({411} <148> direction). / ({111} <112> orientation) satisfies the relationship of ≧ 0.65, and has a magnetic property in which the X value defined by the following formulas (2) to (4) is 0 or more. To provide a non-oriented electrical steel sheet.
Si + Al + 0.5 × Mn ≧ 1.5 (1)
_{W10 / 400} = ( _{W10 / 400L} + 2 × _{W10 / 400D} + _{W10 / 400C} ) / 4 (2)
_{B 50 = (B 50L + 2} × B 50D + B 50C) / 4 (3)
X = 50 × (B ₅₀ + t) −1.4 × W _10/400 −72 (4)
(Here, Si, Al and Mn: Content of each element (% by mass)
W10 _{/ 400L} : Iron loss in the rolling direction when magnetized at an exciting magnetic flux density of 1.0 T and an exciting frequency of 400 Hz (W / kg)
W _{10 / 400C} : Iron loss in the direction perpendicular to the rolling direction when magnetized at an exciting magnetic flux density of 1.0 T and an exciting frequency of 400 Hz (W / kg)
W _{10 / 400D} : Iron loss in 45 ° direction with respect to the rolling direction when magnetized at an exciting magnetic flux density of 1.0 T and an exciting frequency of 400 Hz (W / kg)
B _50L : Magnetic flux density in the rolling direction when magnetized at a magnetization force of 5000 A / m (T)
B _50C : Magnetic flux density (T) in the direction perpendicular to the rolling when magnetized at a magnetization force of 5000 A / m
B _50D : magnetic flux density (T) in the direction of 45 ° with respect to the rolling direction when magnetized with a magnetization force of 5000 A / m
t: plate thickness (mm)
It is. )

  In the above invention, the chemical composition is one or two selected from the group consisting of Sn: 0.2% or less and Sb: 0.2% or less by mass% instead of a part of the Fe. May be contained.

  Further, in the present invention, the above-mentioned chemical composition is a group consisting of Cr: 10.0% or less, Cu: 5.0% or less, and Ni: 5.0% or less by mass% instead of a part of the Fe. One or two or more selected from the following may be contained.

  Further, in the present invention, the above-mentioned chemical composition is a group consisting of Ca: 0.01% or less, Mg: 0.01% or less, and REM: 0.01% or less by mass% instead of a part of the Fe. One or two or more selected from the following may be contained.

  Further, in the present invention, the chemical composition may be such that Ti: 0.010% or less, V: 0.010% or less, Nb: 0.010% or less, and Zr: One or two or more selected from the group consisting of 0.010 or less and Se: 0.010% or less may be contained.

The present invention also provides a method for producing a non-oriented electrical steel sheet, comprising the following steps (A1) and (B) to (D).
(A1) Final pre-cold-rolling annealing in which a steel sheet having the above-described chemical composition before final cold-rolling is maintained in a temperature range of 700 ° C to 900 ° C for 1 hour to 100 hours. Process;
(B) a final cold-rolling step of subjecting the annealed steel sheet obtained by the above-mentioned annealing step before final cold-rolling to a cold-rolling rate of 55% or more and 95% or less to obtain a finished sheet thickness;
(C) a recovery annealing step in which the cold-rolled steel sheet obtained in the final cold rolling step is subjected to recovery annealing for maintaining the temperature range of 350 ° C. to 575 ° C. for 1 hour to 200 hours; and (D) the recovery A finish annealing step of subjecting the annealed steel sheet obtained in the annealing step to a finish annealing in which the steel sheet is held in a temperature range of 800 ° C to 1200 ° C for 1 second to 600 seconds.

Further, the present invention provides a method for producing a non-oriented electrical steel sheet, comprising the following step (A2) instead of the above step (A1).
(A2) The steel sheet before the final cold rolling having the above-described chemical composition is subjected to a final pre-cold-rolling annealing in which the steel sheet is maintained in a temperature range of 850 ° C. to 1200 ° C. for 1 second to 600 seconds. Process.

  Here, the “final cold rolling step” is a cold rolling step in which the finished plate thickness is obtained by the cold rolling, and in the case of continuous multiple-pass cold rolling, the cold rolling of the multiple passes is performed. This is the entire process of applying. Note that “continuous” is intended to exclude intermediate annealing between passes, and does not specify the length of time between passes. That is, the continuous multiple-pass cold rolling may be performed not only by tandem cold rolling but also by reversal cold rolling. The “annealing step before final cold rolling” is an annealing step performed before the final cold rolling step. For example, when a single cold rolling is performed on a hot-rolled steel sheet to obtain a finished sheet thickness, the hot-rolled sheet annealing applied to the hot-rolled steel sheet is annealed before final cold rolling, and the hot-rolled steel sheet is subjected to intermediate annealing. In the case where the cold rolling is performed twice so as to obtain a finished plate thickness, the intermediate annealing is the annealing before the final cold rolling.

  The non-oriented electrical steel sheet according to the present invention can be expected to reduce the size, output, and efficiency of the integrated punching motor. In addition, the method for producing a non-oriented electrical steel sheet according to the present invention does not require special equipment, and is therefore excellent in terms of production cost.

4 is a graph showing a relationship between a recovery annealing temperature and an X value in Example 1.

  Hereinafter, the non-oriented electrical steel sheet of the present invention and the method for producing the same will be described in detail.

A. Non-oriented electrical steel sheet The non-oriented electrical steel sheet of the present invention is, by mass%, C: 0.01% or less, Si: 1.0% or more and 4.0% or less, Al: 0.001% or more and 3.0% or less. %, Mn: 0.05% or more and 3.0% or less, P: 0.15% or less, S: 0.01% or less, N: 0.01% or less, with the balance being Fe and impurities. In addition, it has a chemical composition that satisfies the above formula (1), has a microstructure having an average crystal grain size of 40 μm or more and 250 μm or less, and has a plate thickness of 0.10 mm or more and 0.35 mm or less; The relationship of｝ <148> orientation integrated intensity) / ({111} <112> orientation integrated intensity) ≧ 0.65 is satisfied, and the X value defined by the above equations (2) to (4) is 0 or more. It is characterized by having certain magnetic properties. Hereinafter, the chemical composition and characteristics of the non-oriented electrical steel sheet of the present invention will be described.

1. Chemical Composition First, the reasons for limiting the chemical composition of a steel sheet will be described. Note that “%” indicating the content of each element means “% by mass” unless otherwise specified.

  C is an element contained as an impurity and deteriorating magnetic properties. Therefore, the C content is set to 0.01% or less. Preferably, it is 0.008% or less. More preferably, it is 0.005% or less.

  Si is an element effective for increasing the specific resistance and reducing the iron loss. Therefore, the Si content is set to 1.0% or more. Preferably it is 1.5% or more. On the other hand, since Si is also a solid solution strengthening element, if Si is contained excessively, the ductility of the steel sheet is reduced, and cold rolling becomes difficult. Therefore, the Si content is set to 4.0% or less. Preferably it is 3.5% or less.

  Al is an element effective for increasing the specific resistance and reducing the iron loss. Therefore, the Al content is set to 0.001% or more. Preferably it is 0.01% or more. More preferably, it is at least 0.1%. On the other hand, when Al is excessively contained, the magnetic flux density decreases. Therefore, the Al content is set to 3.0% or less. Preferably it is 2.5% or less.

  Mn is an element effective for increasing the specific resistance and reducing the iron loss. Therefore, the Mn content is set to 0.05% or more. On the other hand, Mn is economically disadvantageous because its alloy cost is higher than that of Si or Al. Therefore, the Mn content is set to 3.0% or less. Preferably it is 2.5% or less. More preferably, it is 2.0% or less.

Since Si, Al, and Mn have an effect of increasing the specific resistance and are effective in reducing iron loss, the contents of Si, Al, and Mn satisfy the following expression (1). It is preferable to satisfy the following expression (1a).
Si + Al + 0.5 × Mn ≧ 1.5 (1)
Si + Al + 0.5 × Mn ≧ 2.0 (1a)

  P is an element generally contained as an impurity. However, P has an effect of improving the texture of the non-oriented electrical steel sheet to improve the magnetic properties, and therefore may be positively contained. However, since P is also a solid solution strengthening element, if the P content is excessive, the ductility of the steel sheet is reduced, and cold rolling becomes difficult. Therefore, the P content is set to 0.15% or less. Preferably it is 0.12% or less. In order to more reliably obtain the effect of the above operation, the P content is preferably set to 0.01% or more. More preferably, it is at least 0.02%.

  S is an element that is contained as an impurity and combines with Mn in steel to form fine MnS, inhibits grain growth during annealing, and deteriorates magnetic properties of a non-oriented electrical steel sheet. Therefore, the S content is set to 0.01% or less. Preferably it is 0.008% or less. More preferably, it is 0.005% or less.

  N is an element that is contained as an impurity element and combines with Al in steel to form fine AlN, inhibits grain growth during annealing, and deteriorates the magnetic properties of the non-oriented electrical steel sheet. Therefore, the N content is set to 0.01% or less. Preferably it is 0.008% or less. More preferably, it is 0.005% or less.

  Sn and Sb have the effect of improving the texture of the non-oriented electrical steel sheet and improving the magnetic properties. Therefore, one or two of Sn and Sb may be contained. However, even if it is contained excessively, the above effect is saturated, which is economically disadvantageous. Therefore, the Sn content is 0.2% or less, and the Sb content is 0.2% or less. The Sn content is preferably at most 0.15%, more preferably at most 0.12%. The Sb content is preferably 0.15% or less, more preferably 0.12% or less. In order to more reliably obtain the effects of the above-described effects, it is preferable that either Sn: 0.001% or more and Sb: 0.001% or more be satisfied, and Sn: 0.002% or more and Sb: 0.002%. It is more preferable that any one of the above is satisfied.

  Cr, Cu and Ni are effective elements for increasing the specific resistance and reducing the iron loss. Therefore, one or more of Cr, Cu and Ni may be contained. However, when Cr, Cu and Ni are excessively contained, the magnetic flux density deteriorates. Therefore, the Cr content is set to 10.0% or less, the Cu content is set to 5.0% or less, and the Ni content is set to 5.0% or less. The Cr content is preferably at most 5.0%, the Cu content is preferably at most 3.0%, and the Ni content is preferably at most 3.0%. In order to more reliably obtain the effect of the above-mentioned effect, it is preferable to satisfy any of Cr: 0.01% or more, Cu: 0.01% or more, and Ni: 0.01% or more, and Cr: 0.02 or more. % Or more, more preferably 0.02% or more of Cu and 0.02% or more of Ni.

  Ca, Mg, and REM are effective elements for controlling inclusions, and when appropriately contained, grain growth during annealing is improved. Therefore, one, two or more of Ca, Mg and REM may be contained. However, even if it is contained excessively, the effect of the above-described action is saturated, and it is economically disadvantageous. Therefore, the Ca content is 0.01% or less, the Mg content is 0.01% or less, and the REM content is 0.01% or less. The Ca content is preferably 0.008% or less, more preferably 0.006% or less. The Mg content is preferably 0.008% or less, more preferably 0.006% or less. The REM content is preferably 0.008% or less, more preferably 0.006% or less. On the other hand, in order to more reliably obtain the effect of the above-mentioned action, it is preferable to satisfy any of Ca: 0.0001% or more, Mg: 0.0001% or more, and REM: 0.0001% or more. It is more preferable that any one of 0.0003% or more, Mg: 0.0003% or more, and REM: 0.0003% or more be satisfied. Here, REM refers to a total of 17 elements including 15 elements of atomic numbers 57 to 71 and 2 elements of Sc and Y.

  Ti, V, Nb, Zr, and Se combine with C, N, Mn, and the like to form inclusions, inhibit growth of crystal grains during annealing, and deteriorate magnetic properties. For this reason, the content of these elements is usually severely restricted. However, according to the present invention, the magnetic properties are dramatically improved, so that the content of any of these elements is allowed up to 0.010%. You. Therefore, the contents of Ti, V, Nb, Zr and Se are all set to 0.010% or less. The content of each element is preferably 0.008% or less, more preferably 0.005% or less.

2. Average crystal grain size Regardless of whether the crystal grain size is too large or too small, iron loss deteriorates. Therefore, the average crystal grain size is 40 μm or more and 250 μm or less. Preferably, it is 50 μm or more and 200 μm or less. The average crystal grain size may be an average value of crystal grain sizes measured by a cutting method in the sheet thickness direction and the rolling direction in a photograph of a longitudinal section structure parallel to the sheet thickness direction and the rolling direction. An optical microscope photograph can be used as the vertical sectional structure photograph, and for example, a photograph taken at a magnification of 50 times may be used.

3. Magnetic properties Iron loss can be reduced by reducing plate thickness and increasing alloy content. However, when the plate thickness is reduced, the number of times of punching during motor production increases, and the productivity decreases. Also, when the content of the alloy element is increased, the ratio of iron atoms in the magnetic steel sheet is reduced, and the magnetic flux density is reduced. That is, iron loss and magnetic flux density, and iron loss and motor productivity generally have a trade-off relationship. Therefore, the balance required for these characteristics depends on the motor design, and when the magnetic flux density is emphasized or when the thickness is increased for motor productivity, the iron loss is relatively small. Is allowed to be higher. For this reason, the present invention is assumed to have magnetic properties in which the X value defined by the following formulas (2) to (4) is 0 or more. The X value is preferably 1 or more.
_{W10 / 400} = ( _{W10 / 400L} + 2 × _{W10 / 400D} + _{W10 / 400C} ) / 4 (2)
_{B 50 = (B 50L + 2} × B 50D + B 50C) / 4 (3)
X = 50 × (B ₅₀ + t) −1.4 × W _10/400 −72 (4)
Here, W _{10 / 400L} : iron loss in the rolling direction when magnetized at an exciting magnetic flux density of 1.0 T and an exciting frequency of 400 Hz (W / kg)
W _{10 / 400C} : Iron loss in the direction perpendicular to the rolling direction when magnetized at an exciting magnetic flux density of 1.0 T and an exciting frequency of 400 Hz (W / kg)
W _{10 / 400D} : Iron loss in 45 ° direction with respect to the rolling direction when magnetized at an exciting magnetic flux density of 1.0 T and an exciting frequency of 400 Hz (W / kg)
B _50L : Magnetic flux density in the rolling direction when magnetized with a magnetization force of 5000 A / m (T)
B _50C : Magnetic flux density (T) in the direction perpendicular to the rolling when magnetized at a magnetization force of 5000 A / m
B _50D : Magnetic flux density (T) in the 45 ° direction with respect to the rolling direction when magnetized at a magnetization force of 5000 A / m
t: Plate thickness (mm).

4. As described above, compressor motors for air conditioners and refrigerators, drive motors for electric vehicles and hybrid vehicles, and generators are used in the high-speed rotation range. It is desirable that the iron loss is low. It is preferable that the sheet thickness be small in order to reduce iron loss under high frequency conditions. Therefore, the plate thickness is set to 0.35 mm or less. Preferably it is 0.33 mm or less. More preferably, it is 0.30 mm or less. On the other hand, excessive thinning significantly reduces the productivity of steel plates and motors. Therefore, the plate thickness is set to 0.10 mm or more. Preferably it is 0.15 mm or more. More preferably, it is 0.20 mm or more.

5. Texture The above formulas (2) and (3) of the present invention indicate the average magnetic properties in the plane of the steel sheet. It is not preferable to excessively increase the anisotropy of the magnetic properties in the plane of the steel sheet, and the {111} <112> and {411} <148> directions, which are the directions in which the anisotropy of the magnetic properties in the plane of the steel sheet is small, are not preferable. Required. Further, among these, it is necessary to reduce the {111} <112> azimuth which adversely affects the magnetic characteristics. Therefore, in order to obtain the magnetic characteristics of the present invention, the ({411} <148> direction) is a ratio of the ({411} <148> direction integrated intensity) to the ({111} <112> direction) integrated intensity. (Integrated intensity of (111) <112> orientation) needs to be 0.65 or more. The ratio of ({411} <148> azimuth) / ({111} <112> azimuth) is preferably 0.80 or more, more preferably 1.0 or more.

  The integrated intensity of the above orientation is obtained from the crystal orientation distribution function (ODF) analyzed from the pole figure obtained by the X-ray diffraction method, and includes {110}, {200}, {211} and {310} pole figures. May be used. In a thin material having a small thickness, which is an object of the present invention, the crystal orientation distribution in the thickness direction is small, and the position at which the pole figure is measured is １ ／ of the thickness.

6. Method for Producing Non-oriented Electrical Steel Sheet The non-oriented electrical steel sheet of the present invention is preferably produced by a method for producing a non-oriented electrical steel sheet described below.

B. Method for Producing Non-Oriented Electrical Steel Sheet The method for producing a non-oriented electrical steel sheet of the present invention has two modes according to the annealing step before final cold rolling.
The first aspect of the method for producing a non-oriented electrical steel sheet of the present invention includes the following steps (A1) and (B) to (D).
(A1) Final pre-cold-rolling annealing in which a steel sheet having the above-described chemical composition before final cold-rolling is maintained in a temperature range of 700 ° C to 900 ° C for 1 hour to 100 hours. Process;
(B) a final cold-rolling step of subjecting the annealed steel sheet obtained by the above-mentioned annealing step before final cold-rolling to a cold-rolling rate of 55% or more and 95% or less to obtain a finished sheet thickness;
(C) a recovery annealing step in which the cold-rolled steel sheet obtained in the final cold rolling step is subjected to recovery annealing for maintaining the temperature range of 350 ° C. to 575 ° C. for 1 hour to 200 hours; and (D) the recovery A finish annealing step of subjecting the annealed steel sheet obtained in the annealing step to a finish annealing in which the steel sheet is held in a temperature range of 800 ° C to 1200 ° C for 1 second to 600 seconds.

The second aspect of the method for producing a non-oriented electrical steel sheet of the present invention includes the following step (A2) instead of the above step (A1).
(A2) The steel sheet before the final cold rolling having the above-described chemical composition is subjected to a final pre-cold-rolling annealing in which the steel sheet is maintained in a temperature range of 850 ° C. to 1200 ° C. for 1 second to 600 seconds. Process.
Hereinafter, each step in the method for producing a non-oriented electrical steel sheet of the present invention will be described.

1. Annealing Step Before Final Cold Rolling In the annealing step before final cold rolling, the steel sheet having the above-described chemical composition is annealed at a temperature of 700 ° C. or more and 900 ° C. or less for 1 hour or more and 100 hours or less. Annealing is performed at a temperature of 1 second to 600 seconds. If the annealing temperature in the annealing step before final cold rolling is low or the annealing time is short, it is difficult to obtain the desired magnetic properties. On the other hand, if the annealing temperature is high, special equipment is required, and if the annealing time is long, the productivity is reduced, which is economically disadvantageous.

  As described above, for example, when the finished sheet thickness is obtained by one cold rolling, the hot rolled sheet annealing corresponds to the annealing before the final cold rolling, and the finished sheet thickness is obtained by two cold rolling steps including the intermediate annealing. In this case, the intermediate annealing corresponds to the annealing before the final cold rolling.

2. Final Cold Rolling Step In the final cold rolling step, the annealed steel sheet obtained by the above-mentioned annealing step before the final cold rolling is subjected to cold rolling at a cold pressure ratio of 55% to 95%. If the cooling pressure ratio in the final cold rolling step is less than 55%, it is difficult to obtain the desired magnetic properties. On the other hand, when the cold pressure ratio in the final cold rolling step is more than 95%, the steel sheet is excessively hardened by the cold rolling, so that the cold rolling becomes difficult. A preferred cooling pressure ratio is 60% or more and 93% or less.

  As described above, the final cold rolling step is a cold rolling step in which the finished plate thickness is obtained by the cold rolling, and when the finished plate thickness is obtained by one cold rolling, the cold rolling is performed in the final cold rolling. In the case where the finished plate thickness is obtained by performing two cold rollings sandwiching the intermediate annealing, the second cold rolling corresponds to the final cold rolling.

3. Recovery Annealing Step In the recovery annealing step, the cold-rolled steel sheet obtained by the final cold rolling step is subjected to recovery annealing at a temperature of 350 ° C. to 575 ° C. for 1 hour to 200 hours. If the annealing temperature in the recovery annealing step is low or the holding time is short, a sufficient recovery structure cannot be obtained, and it is difficult to obtain the desired magnetic properties. On the other hand, when the annealing temperature is high or the holding time is long, recrystallization occurs, and it is difficult to obtain the desired magnetic properties. The annealing temperature is preferably from 400 ° C. to 550 ° C., and the holding time is preferably from 1 hour to 100 hours.

4. Finish Annealing Step In the finish annealing step, the annealed steel sheet obtained by the above-described recovery annealing step is subjected to finish annealing in a temperature range of 800 ° C. to 1200 ° C. for 1 second to 600 seconds. If the annealing temperature in the finish annealing step is low or the annealing time is short, the average crystal grain size will be less than 40 μm, and it will be difficult to obtain the desired magnetic properties. On the other hand, special equipment is required to perform annealing at more than 1200 ° C., and if the holding time is long, the productivity is reduced, which is economically disadvantageous.

5. Hot Rolling Step When preparing a steel sheet having the above chemical composition before final cold rolling, a hot rolling step is usually performed. In hot rolling, steel having the above chemical composition is formed into a slab by a general method such as a continuous casting method or a method of slab-rolling a steel ingot, and is charged into a heating furnace and subjected to hot rolling. At this time, when the slab temperature is high, hot rolling may be performed without charging the furnace. Various conditions of the hot rolling are not particularly limited.

6. Hot Rolled Sheet Annealing Step In the present invention, when the finish sheet thickness is obtained by one cold rolling, a hot rolled sheet annealing step is performed as the final cold rolling pre-annealing step before the final cold rolling step. . On the other hand, in the case where the thickness of the finished sheet is obtained by performing two cold rolling steps including the intermediate annealing, the hot-rolled sheet annealing step is an optional step. In the case where the finished sheet thickness is obtained by performing two cold rolling steps with intermediate annealing, in the hot-rolled sheet annealing step, the box-type annealing is performed by holding the hot-rolled steel sheet in a temperature range of 700 ° C. to 900 ° C. for 1 hour to 100 hours. Preferably, continuous annealing is performed in a temperature range of 800 ° C. to 1200 ° C. for 1 second to 600 seconds. As described above, when the finished sheet thickness is obtained by one cold rolling, the hot rolled sheet annealing step corresponds to the annealing step before the final cold rolling.

7. Other Steps After the above-mentioned finish annealing step, according to a general method, a coating for applying an insulating coating made of only an organic component, only an inorganic component, or an organic-inorganic composite to the steel sheet surface may be applied. From the viewpoint of reducing the environmental load, an insulating film containing no chromium may be applied. Further, the coating may be an insulating coating which exerts an adhesive ability by heating and pressing. An acrylic resin, a phenol resin, an epoxy resin, a melamine resin, or the like can be used as a coating material that exhibits an adhesive ability.

  The present invention is not limited to the above embodiment. The above embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and has the same effect. Within the technical scope of

  Hereinafter, the present invention will be specifically described by way of examples and comparative examples.

[Example 1]
C: 0.002%, Si: 2.0%, Al: 0.3%, Mn: 0.2%, P: 0.01%, S: 0.003%, N: 0.002%, balance A hot rolled steel sheet having a thickness of 2.0 mm is subjected to pickling by hot rolling a slab having a chemical composition of Fe and impurities. After hot-rolled sheet annealing (annealing before final cold rolling) held at 750 ° C. for 10 hours, the pickled sheets are cold-rolled to a sheet thickness of 0.30 mm (cooling ratio: 85%). A part of the obtained cold-rolled steel sheet is not subjected to recovery annealing, and the rest is subjected to recovery annealing for holding for 10 hours in a temperature range of 300 ° C. or more and 600 ° C. or less, and then finish annealing for 10 seconds at 1050 ° C. To obtain a non-oriented electrical steel sheet having an average crystal grain size of 100 μm. With respect to these non-oriented electrical steel sheets, iron losses W _{10 / 400L} , W _{10 / 400C} and W _{10 / 400D} in the L direction, C direction and D direction when magnetized at an excitation magnetic flux density of 1.0 T and an excitation frequency of 400 Hz, The magnetic flux densities B _50L , B _50C and B _50D in the L direction, C direction and D direction when magnetized at a magnetization force of 5000 A / m are measured, and W _10/400 , B _50B are calculated using the equations (2) to (4). Calculate ₅₀ and X value. Also, {110}, {200}, {211}, and {310} pole figures were measured by the X-ray diffraction method at the plate thickness 1/4 position, and the integrated intensity in the ({411} <148> direction) was measured from the ODF. (Integrated intensity in the {411} <148> direction) / (integrated intensity in the {111} <112> direction), which is the ratio of (integrated intensity in the {111} <112> direction), is determined as the integrated intensity ratio. Table 1 shows the results together with the recovery annealing conditions. FIG. 1 shows the relationship between the X value and the recovery annealing temperature.

  Steel sheet No. Steel sheet No. 1 has not been subjected to recovery annealing. Steel sheet No. 2 has a low recovery annealing temperature. No. 5 cannot obtain desired magnetic properties because the recovery annealing temperature is high. Steel sheet No. In Nos. 3 and 4, the recovery annealing conditions are within a predetermined range, so that desired magnetic properties can be obtained.

[Example 2]
A slab having the chemical composition shown in Table 2 is formed into a hot-rolled steel sheet having a thickness of 2.0 to 2.5 mm by hot rolling. Some of these hot-rolled steel sheets are pickled and then subjected to box-type hot-rolled annealing at a temperature of 650 ° C. to 850 ° C. for 10 hours to 30 hours, and the rest 800 ° C. to 1100 ° C. After performing continuous type hot-rolled sheet annealing at a temperature below 30 seconds to 180 seconds, pickling is performed. A cold rolled steel sheet having a thickness of 0.20 mm or more and 0.35 mm or less is formed by subjecting these annealed sheets or pickled sheets to cold rolling. After subjecting these cold-rolled steel sheets to recovery annealing at a temperature of 500 ° C. for 10 hours, finish annealing is performed at 750 ° C. to 1130 ° C. for 5 seconds to 60 seconds to obtain non-oriented electrical steel sheets. These non-oriented electrical steel _sheet, measuring the _{W 10/400} and _{B 50.} Also, {110}, {200}, {211}, and {310} pole figures were measured by the X-ray diffraction method at the plate thickness 1/4 position, and the integrated intensity in the ({411} <148> direction) was measured from the ODF. (Integrated intensity in the {411} <148> direction) / (integrated intensity in the {111} <112> direction), which is the ratio of (integrated intensity in the {111} <112> direction), is determined as the integrated intensity ratio. Table 3 shows the results together with the production conditions.

  Steel sheet No. Nos. 8 and 10 have low hot-rolled sheet annealing temperatures (annealing temperatures before final cold rolling). No. 12 cannot obtain desired magnetic properties because the finish annealing temperature is low.

[Example 3]
C: 0.002%, Si: 3.0%, Al: 1.0%, Mn: 0.2%, P: 0.005%, S: 0.002%, N: 0.002%, balance Is made of Fe and impurities, and a slab having a chemical composition further containing the elements shown in Table 4 is formed into a hot-rolled steel sheet having a thickness of 1.8 mm by hot rolling. These hot-rolled steel sheets are subjected to hot-rolled sheet annealing (annealing before final cold rolling) for 60 seconds at a temperature of 1000 ° C., and then to pickling. These pickled sheets are subjected to cold rolling to form cold-rolled steel sheets having a thickness of 0.25 mm (cooling ratio: 86.1%). These cold-rolled steel sheets are subjected to recovery annealing at a temperature of 475 ° C. for 50 hours, and then to finish annealing at a temperature of 1000 ° C. for 15 seconds to obtain non-oriented electrical steel sheets. These non-oriented electrical steel _sheet, measuring the _{W 10/400} and _{B 50.} Also, {110}, {200}, {211}, and {310} pole figures were measured by the X-ray diffraction method at the plate thickness 1/4 position, and the integrated intensity in the ({411} <148> direction) was measured from the ODF. (Integrated intensity in the {411} <148> direction) / (integrated intensity in the {111} <112> direction), which is the ratio of (integrated intensity in the {111} <112> direction), is determined as the integrated intensity ratio. Table 4 shows the results together with the chemical composition.

  Steel sheet No. As shown in 14 to 21, even if Sn, Sb, Cu, Ni, Cr, Ca, Mg, and REM are added for the purpose of controlling the texture, increasing the specific resistance, and improving the magnetic properties by controlling inclusions, the desired magnetic properties are obtained. Can be obtained.

[Example 4]
C: 0.002%, Si: 2.5%, Al: 1.5%, Mn: 0.2%, P: 0.005%, S: 0.003%, N: 0.003%, balance Is made of Fe and impurities, and a slab having a chemical composition further containing the elements shown in Table 5 is formed into a hot-rolled steel sheet having a thickness of 1.8 mm by hot rolling. After pickling these hot-rolled steel sheets, hot-rolled sheet annealing (annealing before final cold rolling) is performed at 800 ° C. for 10 hours. These annealed sheets are cold-rolled into cold-rolled steel sheets having a thickness of 0.30 mm (cooling ratio: 83.3%). These cold-rolled steel sheets are subjected to recovery annealing at a temperature of 525 ° C. for 5 hours, and then to finish annealing at a temperature of 1050 ° C. for 30 seconds to obtain non-oriented electrical steel sheets. These non-oriented electrical steel _sheet, measuring the _{W 10/400} and _{B 50.} Also, {110}, {200}, {211}, and {310} pole figures were measured by the X-ray diffraction method at the plate thickness 1/4 position, and the integrated intensity in the ({411} <148> direction) was measured from the ODF. (Integrated intensity in the {411} <148> direction) / (integrated intensity in the {111} <112> direction), which is the ratio of (integrated intensity in the {111} <112> direction), is determined as the integrated intensity ratio. Table 5 shows the results together with the chemical composition.

  Steel sheet No. As shown in FIG. 22, if the contents of Ti, V, Nb, Zr and Se are within a predetermined range, desired magnetic properties can be obtained. As shown in 23 to 25, when the contents of Ti, V, Nb, Zr and Se are out of the predetermined ranges, desired magnetic properties cannot be obtained.

[Example 5]
A slab having the chemical compositions of A and D shown in Table 2 is hot-rolled into a hot-rolled steel sheet having a thickness of 2.0 mm. A part of the hot-rolled steel sheet was subjected to box-type hot-rolled sheet annealing maintained at a temperature of 800 ° C. for 20 hours after pickling, and a part was subjected to a continuous-type hot-rolled sheet annealing maintained at 1000 ° C. for 30 seconds. After that, it is pickled. These annealed sheets and pickled sheets are subjected to cold rolling to form cold-rolled steel sheets having an intermediate sheet thickness of 0.5 mm or more and 1.2 mm or less. Part of the obtained cold-rolled steel sheet is subjected to a box-shaped intermediate annealing maintained at 800 ° C. for 20 hours, and the remaining is subjected to a continuous-type intermediate annealing maintained at 1000 ° C. for 30 seconds (annealing before final cold rolling). . The obtained annealed sheet is subjected to cold rolling to obtain a cold-rolled steel sheet having a finished sheet thickness of 0.25 mm or more and 0.30 mm or less. The obtained cold-rolled steel sheet is subjected to recovery annealing at 500 ° C. for 5 hours, and then subjected to finish annealing at 1050 ° C. for 30 seconds to obtain a non-oriented electrical steel sheet having an average crystal grain size of 100 to 115 μm. And For these non-oriented electrical steel sheets, W _10/400 and B ₅₀ are measured, and the X value is calculated. Also, {110}, {200}, {211}, and {310} pole figures were measured by the X-ray diffraction method at the plate thickness 1/4 position, and the integrated intensity in the ({411} <148> direction) was measured from the ODF. (Integrated intensity in the {411} <148> direction) / (integrated intensity in the {111} <112> direction), which is the ratio of (integrated intensity in the {111} <112> direction), is determined as the integrated intensity ratio. Table 6 shows the results together with the production conditions.

  Steel sheet No. No. 27 cannot obtain desired magnetic properties because of a low final cooling pressure ratio.

Claims (7)

In mass%, C: 0.01% or less, Si: 1.0% or more and 4.0% or less, Al: 0.001% or more and 3.0% or less, Mn: 0.05% or more and 3.0% or less , P: 0.15% or less, S: 0.01% or less, N: 0.002% or more and 0.01% or less, the balance being Fe and impurities, and satisfying the following formula (1). Has a chemical composition,
Having a microstructure having an average crystal grain size of 40 μm or more and 250 μm or less,
The board thickness is 0.10 mm or more and 0.35 mm or less,
({411} <148> azimuth integrated strength) / ({111} <112> azimuth integrated strength) : satisfying a relationship of 1.01 or more and 1.51 or less ,
A non-oriented electrical steel sheet having magnetic properties in which the X value defined by the following formulas (2) to (4) is 0 or more.
Si + Al + 0.5 × Mn ≧ 1.5 (1)
_{W10 / 400} = ( _{W10 / 400L} + 2 × _{W10 / 400D} + _{W10 / 400C} ) / 4
(2)
_{B 50 = (B 50L + 2} × B 50D + B 50C) / 4 (3)
X = 50 × (B ₅₀ + t) −1.4 × W _10/400 −72 (4)
(Here, Si, Al and Mn: Content of each element (% by mass)
W10 _{/ 400L} : Iron loss in the rolling direction when magnetized at an exciting magnetic flux density of 1.0 T and an exciting frequency of 400 Hz (W / kg)
W _{10 / 400C} : Iron loss in the direction perpendicular to the rolling direction when magnetized at an exciting magnetic flux density of 1.0 T and an exciting frequency of 400 Hz (W / kg)
W _{10 / 400D} : Iron loss in 45 ° direction with respect to the rolling direction when magnetized at an exciting magnetic flux density of 1.0 T and an exciting frequency of 400 Hz (W / kg)
B _50L : Magnetic flux density in the rolling direction when magnetized at a magnetization force of 5000 A / m (T)
B _50C : Magnetic flux density (T) in the direction perpendicular to the rolling when magnetized at a magnetization force of 5000 A / m
B _50D : magnetic flux density (T) in the direction of 45 ° with respect to the rolling direction when magnetized with a magnetization force of 5000 A / m
t: plate thickness (mm)
It is. )   The chemical composition may contain one or two selected from the group consisting of Sn: 0.2% or less and Sb: 0.2% or less by mass% instead of a part of the Fe. The non-oriented electrical steel sheet according to claim 1.   One kind in which the chemical composition is selected from the group consisting of Cr: 10.0% or less, Cu: 5.0% or less, and Ni: 5.0% or less by mass% instead of part of the Fe; The non-oriented electrical steel sheet according to claim 1, wherein the non-oriented electrical steel sheet contains two or more kinds.   One kind in which the chemical composition is selected from the group consisting of Ca: 0.01% or less, Mg: 0.01% or less, and REM: 0.01% or less by mass% instead of a part of the Fe; 4. The non-oriented electrical steel sheet according to claim 1, wherein the non-oriented electrical steel sheet contains two or more types. 5.   The chemical composition is, instead of part of the Fe, by mass%, Ti: 0.010% or less, V: 0.010% or less, Nb: 0.010% or less, Zr: 0.010 or less, and Se. The non-oriented electrical steel sheet according to any one of claims 1 to 4, comprising one or more selected from the group consisting of: 0.010% or less. A method for producing a non-oriented electrical steel sheet for producing the non-oriented electrical steel sheet according to any one of claims 1 to 5,
A method for producing a non-oriented electrical steel sheet, comprising the following steps (A1) and (B) to (D):
(A1) A final cold-rolled steel sheet having the chemical composition according to any one of claims 1 to 5, which is maintained in a temperature range of 700 ° C to 900 ° C for 1 hour to 100 hours, before the final cold rolling. Final pre-cold-rolling annealing step of performing pre-rolling annealing;
(B) a final cold rolling step of subjecting the annealed steel sheet obtained by the annealing step before the final cold rolling to cold rolling at a cold pressure ratio of 55% or more and 95% or less to obtain a finished sheet thickness;
(C) a recovery annealing step in which the cold-rolled steel sheet obtained in the final cold rolling step is subjected to recovery annealing for maintaining the temperature in a temperature range of 350 ° C to 575 ° C for 1 hour to 200 hours; and (D) the recovery A finish annealing step of subjecting the annealed steel sheet obtained in the annealing step to a finish annealing in which the steel sheet is held in a temperature range of 800 ° C to 1200 ° C for 1 second to 600 seconds. A method for producing a non-oriented electrical steel sheet for producing the non-oriented electrical steel sheet according to any one of claims 1 to 5,
A method for producing a non-oriented electrical steel sheet, comprising the following steps (A2) and (B) to (D):
(A2) A final cold-rolled steel sheet having the chemical composition according to any one of claims 1 to 5, which is maintained in a temperature range of 850 ° C or more and 1200 ° C or less for 1 second or more and 600 seconds or less. Final pre-cold-rolling annealing step of performing pre-rolling annealing;
(B) a final cold rolling step of subjecting the annealed steel sheet obtained by the annealing step before the final cold rolling to cold rolling at a cold pressure ratio of 55% or more and 95% or less to obtain a finished sheet thickness;
(C) a recovery annealing step in which the cold-rolled steel sheet obtained in the final cold rolling step is subjected to recovery annealing for maintaining the temperature in a temperature range of 350 ° C to 575 ° C for 1 hour to 200 hours; and (D) the recovery A finish annealing step of subjecting the annealed steel sheet obtained in the annealing step to a finish annealing in which the steel sheet is held in a temperature range of 800 ° C to 1200 ° C for 1 second to 600 seconds.